tooltip_div blocks mouse events from underlying nodes when faded out by opacity

[unverbuggt]

The tooltip_div is faded in by a mouseover event and faded out by mouseout on a node or its text. I've noticed that while the div is hidden by setting opacity:0 it still blocks mouse events from happening on nodes it previously covered. Only by setting visibility:hidden the div will stop blocking mouse events on underlying nodes. I've made too much specific changes in my fork to be able to create a pull request (Also I'm not too much of a git expert). But here are the changes I made to circumvent this: https://github.com/unverbuggt/mkdocs-familytree-example/commit/ea56f2e3f74984094f845d7f44705829480ea82b

[BenPortner]

Thanks a lot @unverbuggt! Should be fixed with https://github.com/BenPortner/js_family_tree/commit/211d1a4de08ebb6f53f976ab9a3c4e28583e019d. Feel free to re-open, if it isn't.